Ducks said it right - bubble nests, completely normal. Bettas are 'top' feeder fish, they prefer to stay near the top.
Some tips:
- Bettas are not really flake eaters, get something called Hakari Bio-Gold (small brown/gold floating ball food). They can eat between 6 to 9 a day, give or take. This brand will float for quite some time, and reduce the amount of waste food loss (flakes piling up at the bottom) You can also use live or frozen foods like micro-worms. Bettas are meat-eats.
- These are tropical fish, dont let them get chilled at night. About 78 to 80F is preferred with no drastic changes.
Let us know what size of tank (inches or gallons preferred), so we can suggest a water change schedule that best fits.
If you have your betta in one of those Vase things (plant on top) get him into a proper tank right away, something like a 2gal acrylic tank or bigger. Vases setups will eventually kill the betta (any fish in fact)
These are great fish, but be sure to read-up on how to care for them.
Some links...
http://www.bettastarz.com/adultcare.htm
Oh, and welcome to the Tank!